Selectively sending updated data values

ABSTRACT

A processing system, computer program product, and methods for maintaining consistent values of objects in two or more stores. A method includes a data store associating an updated-version-request-time for each object of a plurality of objects wherein each object of the plurality of objects resides on the data store. The data store maintains a data structure ordering the plurality of objects by updated-version-request-times. The data store periodically examines the data structure to read updated-version-request-times. The data store makes a decision to notify another data store of a change to an object belonging to the plurality of objects based on an updated-version-request-time of the object. The data structure can be a balanced tree.

BACKGROUND

The present invention generally relates to data stores, data caching,and file storage systems, in computer systems. Many data stores existsuch as SQL data stores, NoSQL data stores, caches, and file systems. Ifmultiple data stores are being used, a key problem is how to synchronizedata values so that the same values are maintained in the data stores. Amethod is needed to synchronize data values maintained in multiple datastores.

BRIEF SUMMARY

According to various embodiments, disclosed is a method for maintainingconsistent values of objects, the method comprising: a data storeassociating an updated-version-request-time for each object of aplurality of objects wherein each object of the plurality of objectsresides on the data store; the data store maintaining a data structureordering the plurality of objects by updated-version-request-times; thedata store periodically examining the data structure to readupdated-version-request-times; and the data store making a decision tonotify another data store of a change to an object belonging to theplurality of objects based on an updated-version-request-time of theobject.

According to various embodiments, disclosed is a processing systemcomprising: a server; memory; a network interface device forcommunicating with one or more networks; and at least one processor,communicatively coupled with the server, the memory, and the networkinterface device, the at least one processor, responsive to executingcomputer instructions, for performing operations comprising: a datastore associating an updated-version-request-time for each object of aplurality of objects wherein each object of the plurality of objectsresides on the data store; the data store maintaining a data structureordering the plurality of objects by updated-version-request-times; thedata store periodically examining the data structure to readupdated-version-request-times; and the data store making a decision tonotify another data store of a change to an object belonging to theplurality of objects based on an updated-version-request-time of theobject.

According to various embodiments, disclosed is a computer programproduct for a processing system, the computer program product comprisinga computer readable storage medium having computer readable program codeembodied therewith, the computer readable program code includingcomputer instructions, where a processor, responsive to executing thecomputer instructions, performs operations comprising: a data storeassociating an updated-version-request-time for each object of aplurality of objects wherein each object of the plurality of objectsresides on the data store; the data store maintaining a data structureordering the plurality of objects by updated-version-request-times; thedata store periodically examining the data structure to readupdated-version-request-times; and the data store making a decision tonotify another data store of a change to an object belonging to theplurality of objects based on an updated-version-request-time of theobject.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures wherein reference numerals refer to identicalor functionally similar elements throughout the separate views, andwhich together with the detailed description below are incorporated inand form part of the specification, serve to further illustrate variousembodiments and to explain various principles and advantages all inaccordance with the present invention, in which:

FIG. 1 is a block diagram illustrating an example of a plurality of datastores, according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating an example of another pluralityof data stores, according to an embodiment of the present invention;

FIG. 3 is a block diagram illustrating an example of a method forsynchronizing data values, according to an embodiment of the presentinvention;

FIG. 4 is a block diagram illustrating an example of another method forsynchronizing data values, according to an embodiment of the presentinvention;

FIG. 5 is a block diagram illustrating an example processing system,according to an embodiment of the present invention

FIG. 6 depicts a cloud computing environment suitable for use in anembodiment of the present invention; and

FIG. 7 depicts abstraction model layers according to the cloud computingembodiment of FIG. 6.

DETAILED DESCRIPTION

As required, detailed embodiments are disclosed herein; however, it isto be understood that the disclosed embodiments are merely examples andthat the systems and methods described below can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present subject matter in virtually anyappropriately detailed structure and function. Further, the terms andphrases used herein are not intended to be limiting, but rather, toprovide an understandable description of the concepts.

The description of the present invention has been presented for purposesof illustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiments were chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated. The terminology used herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting of the invention.

Various embodiments of the present invention are applicable tosynchronizing data values between two or more data stores in a widevariety of environments, which may include cloud computing environmentsand non-cloud environments. According to various embodiments of theinvention, provided is the capability to synchronize values between twoor more data stores. The term data store is intended to broadly includesa wide variety of systems for storing data, such as but not limited to,MySQL, DB2, Cassandra, Cloudant, file systems, memcached, redis, andmany other systems. Furthermore, throughout this patent application, adata store can include both the software used for storing data as wellas one or more computers on which the software runs.

FIG. 3 shows a method for synchronizing data values in accordance withthe current invention. The method can be used by the system in FIG. 1.Data store 1 101 is caching copies of objects which reside in other datastores. For example, object o1 might reside in data store 2 103. Sincedata store 1 101 is using object o1, it caches object of so that it doesnot have to fetch object o1 from data store 2 103 each time data store 1101 needs to access object o1. A key problem is that object o1 may bechanging. The current value of object o1 can be found by contacting datastore 2 103. There is overhead for data store 1 101 to contact datastore 2 103. Data store 1 101 thus employs techniques to selectivelycontact data store 2 103 to obtain current values of object o1.

Note that while FIG. 1 depicts three data stores, the number of datastores can be two, three, four, five, or a larger positive integer.

Data store 1 101 maintains update times for objects such as object o1which reside on remote data stores. An update time(updated-version-request-time) for an object is an indication of whendata store 1 101 should contact a remote server to obtain an updatedvalue of object o1. Update times may be based on one or more of severalcriteria. For example, an update time might be an expiration time for anobject provided by the data store on which the object resides.

Update times might be based on how frequently (i.e., a frequency withwhich) an object changes. If an object changes frequently, its updatetime should be sooner than if the object changes less frequently. Thedata store on which the object resides is often in the best position toprovide information on how frequently the object changes.

Update times can also be based on how important it is for a data storeto have the most recent version of an object. For example, if it is veryimportant for data store 1 101 to have an updated copy of object o1,then the update time for object of would be sooner than if it is notimportant for data store 1 101 to have an updated copy of object o1.

Update times can also be based on the cost of obtaining an updatedobject from a remote data store. This cost can be a monetary cost. Itcan also be a bandwidth cost. Large objects consume more bandwidth tofetch than smaller objects, and are thus more costly to fetch. The costcan also be based on computational resources for obtaining currentobjects. For example, it may be computationally expensive for data store2 103 to calculate a current value of object o1.

If the cost of obtaining an updated object from a remote data store islow, then the update time for the object would be sooner than if thecost of obtaining an updated object from a remote data store is high.

Update times can also be based on how frequently (i.e., a frequency withwhich) a data store uses an object. For example, if data store 1 101uses object o1 frequently, then the update time for object o1 would besooner than if data store 1 101 uses object o1 rarely.

Data store 1 101 maintains a data structure ordering update times ofobjects from remote data stores that it has cached. This data structureis depicted as Ordered Update Times data structure 102 in FIG. 1. Thisstep is depicted as 301 in FIG. 3.

In order to order update times of cached objects, an efficient datastructure should be used. Ordered Update Times data structure 102 can beimplemented using a balanced tree, such as an AVL tree, a red-blacktree, or a B-tree (see the relevant articles found online on theWikipedia website).

Ordered Update Times data structure 102 can also be implemented using alist. However, a list will usually not be as efficient as a balancedtree.

In step 302, data store 1 101 periodically examines the Ordered UpdateTimes data structure 102 to determine which objects, if any, should beupdated. Data store 1 101 makes a decision to update an object based onits update time. If the update time is soon or has elapsed, according tothe example, data store 1 101 contacts, in step 303, the remote serveron which the object resides to determine if an updated version of theobject is needed.

One method of determining whether data store 1 101 should contact datastore 2 103 to obtain an updated version of object of is by comparingthe current time to the update time (i.e., the update time which ismaintained in the Ordered Update Times data structure 102) for objecto1. If the difference between the update time for object o1 and thecurrent time is below a threshold value, data store 1 101 contacts datastore 2 103 to see if object of has changed. Otherwise, data store 1 101does not contact data store 2 103.

Data store 1 101 can directly request an updated copy of object of fromdata store 2 103. An alternative is to use entity tags. Object o1 has anentity tag indicating its version. Data store 1 101 contacts data store2 103 for an updated version of object of and sends data store 2 103 itsentity tag for object o1. If the entity tag sent by data store 1 101 iscurrent, data store 2 103 informs data store 1 101 that the cached valueof object of it has is still current. Data store 2 103 does not need tosend an updated value of object of to data store 1 101, which can saveconsiderable network bandwidth.

If the entity tag sent by data store 1 101 is not current, according tothe example, then data store 3 103 sends a current copy of object o1 todata store 1 101.

If object of has been deleted, then this information is provided to datastore 1 101. Data store 1 101 might then delete its copy of object o1.Once an object cached in data store 1 101 is deleted, the update timeand other data associated with the object are also deleted from OrderedUpdate Times data structure 102.

Data store 2 103 might also send an updated expiration time for objectof to data store 1 101. Data store 1 101 can use this expiration time todetermine an update time for object o1. Data store 1 101 can store andmaintain this expiration time information associated with object o1,along with other information associated with object o1, in the OrderedUpdate Times data structure 102.

When multiple objects need to be updated from the same server, it isoften more efficient to perform multiple updates in a single requestthan to perform each update in a separate request. An optimization thussupported by various embodiments of the present invention, is theability to batch multiple updates in response to a single request.Suppose data store 1 101 is caching multiple objects from data store 2103. Suppose that data store 1 101 has determined that x (e.g. x can be7 or another integer>1) of the cached objects have update times whichoccur in close proximity to each other. By close proximity, this canmean that the difference between the latest update time lt and theearliest update time et (corresponding to object oet) for all x objectsis less than a threshold value. Other definitions of close proximity arepossible within the scope of the invention.

When data store 1 101 determines that it is time to query data store 2103 to determine if object oet has changed, data store 1 101 actuallyqueries data store 2 103 to get updates for all x objects in a singlerequest. Data store 2 103 then sends update information for all xobjects in a single response.

FIG. 4 shows another method for synchronizing data values in accordancewith the current invention. The method can be used by the system in FIG.2. Several objects reside in Ordered Update Times data store 4 201. Datastore 5 203 and data store 6 204 can cache data objects residing on datastore 4 201. Data store 4 201 has the ability to contact data store 5203 and data store 6 204 to indicate that one or more objects havechanged. Note that while FIG. 2 depicts three data stores, the number ofdata stores can be two, three, four, five, or a larger positive integer.

Suppose object o1 resides in data store 4 201. Data store 5 203 is usingobject o1 and caches object o1 so that it does not have to fetch objecto1 from data store 4 201 each time data store 5 203 needs to accessobject o1. A key problem is that object o1 may be changing. Data store 4201 can send the current value of object o1 to data store 5 203. Thereis overhead for data store 4 201 to do this. Data store 4 201 thusemploys techniques to selectively contact data store 5 203 to sendcurrent values of object o1.

Data store 4 201 maintains update times for objects such as object o1which reside on data store 4 201 but might be cached in remote datastores. An update time for an object is an indication of when data store4 201 should contact a remote server to notify the remote server ofchanges to object o1. Update times may be based on one or more ofseveral criteria. For example, an update time might be an expirationtime for an object provided by the data store on which the objectresides.

Update times might be based on how frequently an object changes. If anobject changes frequently, its update time should be sooner than if theobject changes less frequently. The data store on which the objectresides is often in the best position to provide information on howfrequently the object changes.

Update times can also be based on how important it is for a data storeto have the most recent version of an object. For example, if it is veryimportant for a data store to have an updated copy of object o1, thenthe update time for object o1 would be sooner than if it is notimportant for a data store to have an updated copy of object o1.

Update times can also be based on the cost of sending an updated objectto a remote data store. This cost can be a monetary cost. It can also bea bandwidth cost. Large objects consume more bandwidth to send thansmaller objects, and are thus more costly to send. The cost can also bebased on computational resources for determining current objects. Forexample, it may be computationally expensive for data store 4 201 tocalculate a current value of object o1.

If the cost of obtaining an updated object from a remote data store islow, then the update time for the object would be sooner than if thecost of obtaining an updated object from a remote data store is high.

Update times can also be based on how frequently (i.e., a frequency withwhich) a data store uses an object. For example, if s data store usesobject o1 frequently, then the update time for object o1 would be soonerthan if the data store uses object o1 rarely.

Data store 4 201 maintains a data structure ordering update times ofobjects from remote data stores that it has cached. This data structureis depicted as Ordered Update Times data structure 202 in FIG. 2. Thisstep is depicted as 401 in FIG. 4.

In order to order update times of cached objects, an efficient datastructure should be used. Ordered Update Times data structure 202 can beimplemented using a balanced tree, such as an AVL tree, a red-blacktree, or a B-tree (see the relevant articles found online on theWikipedia website).

Ordered Update Times data structure 202 can also be implemented using alist. However, a list will usually not be as efficient as a balancedtree.

In step 402, data store 4 201 periodically examines Ordered Update Timesdata structure 202 to determine which object updates, if any, should besent to remote data stores. Data store 4 201 makes a decision to sendinformation about an object based on its update time. If the update timeis soon or has elapsed, data store 4 201 contacts, in step 403, a remoteserver which may be caching the object regarding updates to the object.

One example method of determining whether data store 4 201 shouldcontact data store 5 203 to send information regarding object of is bycomparing the current time to the update time (i.e., the update timewhich is maintained in the Ordered Update Times data structure 202) forobject o1. If the difference between the update time for object o1 andthe current time is below a threshold value, data store 4 201 contactsdata store 5 203 regarding object o1. Otherwise, data store 4 201 doesnot contact data store 5 203.

In step 403, according to the example, sometimes data store 4 201 willknow the exact version of object o1 that data store 5 203 is storing. Ifdata store 5 203 is already storing the current version of object o1,data store 4 201 does not need to send the current version of object ofto data store 5 203. If data store 5 203 is not storing the currentversion of object o1, data store 4 201 can either send the new versionof object o1 to data store 5 203 or simply notify data store 5 203 thatobject o1 has changed.

If data store 4 201 does not know the exact version of object o1 thatdata store 5 203 is storing, data store 4 201 can try to find this outby requesting an entity tag corresponding to object o1 stored by datastore 5 203, entity tag et_o1. If data store 5 203 actually has andreturns entity tag et_o1, data store 4 201 compares entity tag et_o1 tothe current entity tag for object o1. If they match, then data store 4201 does not need to send an updated version of object o1 to data store5 203. If they do not match (or data store 5 203 was not able to returnan entity tag to object o1), then data store 4 201 indicates to datastore 5 203 that the value of object o1 has changed and/or sends a newversion of object o1 to data store 5 203.

If object o1 has been deleted, then this information is provided to datastore 5 203. Data store 5 203 might then delete its copy of object o1.Once an object in data store 4 201 is deleted, the update time and otherdata associated with the object are also deleted from Ordered UpdateTimes data structure 202.

When multiple objects need to be updated on the same server, it is oftenmore efficient to perform multiple updates in a single request than toperform each update in a separate request. An optimization thussupported by various embodiments of the present invention, is theability to batch multiple updates in response to a single request.Suppose data store 5 203 is caching multiple objects from data store 4201. Suppose that data store 4 201 has determined that x (e.g., x can bea value of seven (7) or another integer>1) of the cached objects haveupdate times which occur in close proximity (e.g., close temporalproximity) to each other. By close proximity, according to the presentexample, this can mean that the difference between the latest updatetime lt and the earliest update time et (corresponding to object oet)for all x objects is less than a threshold value. Other definitions ofclose proximity are possible within the scope of the present invention.

When data store 4 201 determines that it is time to send informationregarding object oet (which may include the fact that object oet haschanged and/or an updated value of object oet) to data store 5 203, datastore 4 201 actually sends information regarding all x objects (whichmay identify objects which have changed, and may also include copies ofone or more objects which have changed) to data store 5 203 in a singlerequest.

Example of a Processing System Server Node Operating in a Network

FIG. 5 illustrates an example of a processing system server node 500(also referred to as a computer system/server or referred to as a servernode) suitable for use according to various embodiments of the presentinvention. The server node 500, according to the example, iscommunicatively coupled with a cloud infrastructure 532 that can includeone or more communication networks. The cloud infrastructure 532 iscommunicatively coupled with a storage cloud 534 (which can include oneor more storage servers) and with a computation cloud 536 (which caninclude one or more computation servers). This simplified example is notintended to suggest any limitation as to the scope of use or function ofvarious example embodiments of the invention described herein.

The server node 500 comprises a computer system/server, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with such a computer system/server include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems and/or devices, and the like.

The computer system/server 500 may be described in the general contextof computer system-executable instructions, such as program modules,being executed by a computer system. Generally, program modules mayinclude routines, programs, objects, components, logic, data structures,and so on that perform particular tasks or implement particular abstractdata types. Computer system/server may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

Referring more particularly to FIG. 5, the following discussion willdescribe a more detailed view of an example cloud infrastructure servernode embodying at least a portion of the client-server system of FIG. 1.According to the example, at least one processor 502 is communicativelycoupled with system main memory 504 and persistent memory 506.

A bus architecture 508 facilitates communicatively coupling between theat least one processor 502 and the various component elements of theserver node 500. The bus 508 represents one or more of any of severaltypes of bus structures, including a memory bus or memory controller, aperipheral bus, an accelerated graphics port, and a processor or localbus using any of a variety of bus architectures. By way of example, andnot limitation, such architectures include Industry StandardArchitecture (ISA) bus, Micro Channel Architecture (MCA) bus, EnhancedISA (EISA) bus, Video Electronics Standards Association (VESA) localbus, and Peripheral Component Interconnects (PCI) bus.

The system main memory 504, in one embodiment, can include computersystem readable media in the form of volatile memory, such as randomaccess memory (RAM) and/or cache memory. By way of example only, apersistent memory storage system 506 can be provided for reading fromand writing to a non-removable, non-volatile magnetic media (not shownand typically called a “hard drive”). Although not shown, a magneticdisk drive for reading from and writing to a removable, non-volatilemagnetic disk (e.g., a “floppy disk”), and an optical disk drive forreading from or writing to a removable, non-volatile optical disk suchas a CD-ROM, DVD-ROM or other optical media can be provided. In suchinstances, each can be connected to bus 508 by one or more data mediainterfaces. As will be further depicted and described below, persistentmemory 506 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of various embodiments of the invention.

Program/utility, having a set (at least one) of program modules, may bestored in persistent memory 506 by way of example, and not limitation,as well as an operating system 524, one or more application programs526, other program modules, and program data. Each of the operatingsystem 524, one or more application programs 526, other program modules,and program data, or some combination thereof, may include animplementation of a networking environment. Program modules generallymay carry out the functions and/or methodologies of various embodimentsof the invention as described herein.

The at least one processor 502 is communicatively coupled with one ormore network interface devices 516 via the bus architecture 508. Thenetwork interface device 516 is communicatively coupled, according tovarious embodiments, with one or more networks operably coupled with acloud infrastructure 532. The cloud infrastructure 532, according to theexample, includes a second server 534, which may also be referred to asa second server node on the network, and a third server 536, which mayalso be referred to as a third server node on the network. The networkinterface device 516 can communicate with one or more networks such as alocal area network (LAN), a general wide area network (WAN), and/or apublic network (e.g., the Internet). The network interface device 516facilitates communication between the server node 500 and other servernodes in the cloud infrastructure 532.

A user interface 510 is communicatively coupled with the at least oneprocessor 502, such as via the bus architecture 508. The user interface510, according to the present example, includes a user output interface512 and a user input interface 514. Examples of elements of the useroutput interface 512 can include a display, a speaker, one or moreindicator lights, one or more transducers that generate audibleindicators, and a haptic signal generator. Examples of elements of theuser input interface 514 can include a keyboard, a keypad, a mouse, atrack pad, a touch pad, and a microphone that receives audio signals.The received audio signals, for example, can be converted to electronicdigital representation and stored in memory, and optionally can be usedwith voice recognition software executed by the processor 502 to receiveuser input data and commands.

A computer readable medium reader/writer device 518 is communicativelycoupled with the at least one processor 502. The reader/writer device518 is communicatively coupled with a computer readable medium 520. Theserver node 500, according to various embodiments, can typically includea variety of computer readable media 520. Such media may be anyavailable media that is accessible by the processing system/server 500,and it can include any one or more of volatile media, non-volatilemedia, removable media, and non-removable media.

Computer instructions 507 can be at least partially stored in variouslocations in the server node 500. For example, at least some of theinstructions 507 may be stored in any one or more of the following: inan internal cache memory in the one or more processors 502, in the mainmemory 504, in the persistent memory 506, and in the computer readablemedium 520.

The instructions 507, according to the example, can include computerinstructions, data, configuration parameters, and other information thatcan be used by the at least one processor 502 to perform features andfunctions of the server node 500. According to the present example, theinstructions 507 include an operating system 524 and one or moreapplications 526. The instructions 507 also include an object updater528 which updates objects in the local cache 522 according to themethods that have been discussed above with reference to FIGS. 1-4.Additionally, the instructions 507 include an Object Update OrderManager 530 which, according to the data stored in the Update Order DataStructure 523 in the local cache 522, manages when to update objects inthe local cache 522, e.g., the timing and the order of updating objectsin the local cache 522, according to the methods that have beendiscussed above with reference to FIGS. 1-4. Additionally, theinstructions 507 include server node configuration data (not shown).

The at least one processor 502, according to the example, iscommunicatively coupled with the server cache storage 522 (also referredto as local cache), which can store at least a portion of the servernode data, the Update Order Data Structure 523, networking system andcloud infrastructure messages and data being communicated with theserver node 500, and other data, for operation of services andapplications coupled with the server node 500. Various functions andfeatures of the present invention, as have been discussed above, may beprovided with use of the server node 500.

Example Cloud Computing Environment

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases

automatically, to quickly scale out and rapidly released to quicklyscale in. To the consumer, the capabilities available for provisioningoften appear to be unlimited and can be purchased in any quantity at anytime.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 6, an illustrative cloud computing environment 650is depicted. As shown, cloud computing environment 650 comprises one ormore cloud computing nodes 610 with which local computing devices usedby cloud consumers, such as, for example, personal digital assistant(PDA) or cellular telephone 654A, desktop computer 654B, laptop computer654C, and/or automobile computer system 654N may communicate. Nodes 610may communicate with one another. They may be grouped (not shown)physically or virtually, in one or more networks, such as Private,Community, Public, or Hybrid clouds, or a combination thereof. Thisallows cloud computing environment 650 to offer infrastructure,platforms and/or software as services for which a cloud consumer doesnot need to maintain resources on a local computing device. It isunderstood that the types of computing devices 654A-N shown in FIG. 6are intended to be illustrative only and that computing nodes 610 andcloud computing environment 650 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 7, a set of functional abstraction layers providedby cloud computing environment 650 is shown. It should be understood inadvance that the components, layers, and functions shown in FIG. 7 areintended to be illustrative only and embodiments of the invention arenot limited thereto. As depicted, the following layers and correspondingfunctions are provided:

Hardware and software layer 760 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 761;RISC (Reduced Instruction Set Computer) architecture based servers 762;servers 763; blade servers 764; storage devices 765; and networks andnetworking components 766. In some embodiments, software componentsinclude network application server software 767 and database software768.

Virtualization layer 770 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers771; virtual storage 772; virtual networks 773, including virtualprivate networks; virtual applications and operating systems 774; andvirtual clients 775.

In one example, management layer 780 may provide the functions describedbelow. Resource provisioning 781 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 782provide cost tracking of resources which are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 783 provides access to the cloud computing environment forconsumers and system administrators. Service level management 784provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 785 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 790 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 791; software development and lifecycle management 792;virtual classroom education delivery 793; data analytics processing 794;transaction processing 795; and other data communication and deliveryservices 796. Various functions and features of the present invention,as have been discussed above, may be provided with use of a server node500 communicatively coupled with a cloud infrastructure 532.

Non-Limiting Examples

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Although the present specification may describe components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the invention is not limited to such standards andprotocols. Each of the standards represents examples of the state of theart. Such standards are from time-to-time superseded by faster or moreefficient equivalents having essentially the same functions.

The illustrations of examples described herein are intended to provide ageneral understanding of the structure of various embodiments, and theyare not intended to serve as a complete description of all the elementsand features of apparatus and systems that might make use of thestructures described herein. Many other embodiments will be apparent tothose of skill in the art upon reviewing the above description. Otherembodiments may be utilized and derived therefrom, such that structuraland logical substitutions and changes may be made without departing fromthe scope of this invention. Figures are also merely representationaland may not be drawn to scale. Certain proportions thereof may beexaggerated, while others may be minimized. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement calculated toachieve the same purpose may be substituted for the specific embodimentsshown. The examples herein are intended to cover any and all adaptationsor variations of various embodiments. Combinations of the aboveembodiments, and other embodiments not specifically described herein,are contemplated herein.

The Abstract is provided with the understanding that it is not intendedbe used to interpret or limit the scope or meaning of the claims. Inaddition, in the foregoing Detailed Description, various features aregrouped together in a single example embodiment for the purpose ofstreamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter lies in lessthan all features of a single disclosed embodiment. Thus the followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

Although only one processor is illustrated for an information processingsystem, information processing systems with multiple CPUs or processorscan be used equally effectively. Various embodiments of the presentinvention can further incorporate interfaces that each includesseparate, fully programmed microprocessors that are used to off-loadprocessing from the processor. An operating system included in mainmemory for a processing system may be a suitable multitasking and/ormultiprocessing operating system, such as, but not limited to, any ofthe Linux, UNIX, Windows, and Windows Server based operating systems.Various embodiments of the present invention are able to use any othersuitable operating system. Various embodiments of the present inventionutilize architectures, such as an object oriented framework mechanism,that allow instructions of the components of the operating system to beexecuted on any processor located within an information processingsystem. Various embodiments of the present invention are able to beadapted to work with any data communications connections includingpresent day analog and/or digital techniques or via a future networkingmechanism.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise”,“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. The term “another”, as usedherein, is defined as at least a second or more. The terms “include”,includes”, “including” and “having,” as used herein, are defined ascomprising (i.e., open language). The term “coupled,” as used herein, isdefined as “connected,” although not necessarily directly, and notnecessarily mechanically. “Communicatively coupled” refers to couplingof components such that these components are able to communicate withone another through, for example, wired, wireless or othercommunications media. The terms “communicatively coupled” or“communicatively coupling” include, but are not limited to,communicating electronic control signals by which one element may director control another. The term “configured to” describes hardware,software or a combination of hardware and software that is adapted to,set up, arranged, built, composed, constructed, designed or that has anycombination of these characteristics to carry out a given function. Theterm “adapted to” describes hardware, software or a combination ofhardware and software that is capable of, able to accommodate, to make,or that is suitable to carry out a given function.

The terms “controller”, “computer”, “processor”, “server”, “client”,“computer system”, “computing system”, “personal computing system”,“processing system”, or “information processing system”, describeexamples of a suitably configured processing system adapted to implementone or more embodiments herein. Any suitably configured processingsystem is similarly able to be used by embodiments herein, for exampleand not for limitation, a personal computer, a laptop personal computer(laptop PC), a tablet computer, a smart phone, a mobile phone, awireless communication device, a personal digital assistant, aworkstation, and the like. A processing system may include one or moreprocessing systems or processors. A processing system can be realized ina centralized fashion in one processing system or in a distributedfashion where different elements are spread across severalinterconnected processing systems.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed.

The description of the present application has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. In a system including at least two data stores, amethod for maintaining consistent values of objects, the methodcomprising: a data store associating an updated-version-request-time foreach object of a plurality of objects wherein each object of theplurality of objects resides on the data store; the data storemaintaining a data structure ordering the plurality of objects byupdated-version-request-times; the data store periodically examining thedata structure to read updated-version-request-times; and the data storemaking a decision to notify another data store of a change to an objectbelonging to the plurality of objects based on anupdated-version-request-time of the object.
 2. The method of claim 1further comprising the data store sending an updated copy of the objectto another data store.
 3. The method of claim 1 in which the data storenotifies another data store of a change to the object in response to adifference between the updated-version-request-time and a current timebeing less than a threshold value.
 4. The method of claim 1 in which anupdated-version-request-time for an object is based on a frequency withwhich the object changes.
 5. The method of claim 1 in which anupdated-version-request-time for an object is based on an importance ofmaintaining a current value of the object in a data store.
 6. The methodof claim 1 in which an updated-version-request-time for an object isbased on a frequency with which a data store uses the object.
 7. Themethod of claim 1 in which the data structure is a balanced tree.
 8. Themethod of claim 7 in which the data structure is one of a red-blacktree, an AVL tree, and a B-tree.
 9. The method of claim 1 in which thedata structure is a list.
 10. The method of claim 1 further comprising:the data store requesting an entity tag from a second data storeidentifying a version of the object stored in the second data store; andin response to the entity tag from the second data store not matching anentity tag corresponding to a current version of the object, the datastore sending a current value of the object to the second data store.11. The method of claim 1 in which an updated-version-request-time foran object is based on an expiration time associated with the object. 12.The method of claim 1 in which an updated-version-request-time for anobject is based on a cost of the data store sending an updated versionof the object to a remote data store.
 13. The method of claim 1 furthercomprising: determining a subset including at least two of the pluralityof objects which have updated-version-request-times in close temporalproximity and reside on the data store; and the data store sendingupdated versions of all objects in the subset in a single request. 14.The method of claim 1 in which an updated-version-request-time for anobject is based on a cost of the data store determining an updatedversion of the object.
 15. A computer program product for a processingsystem comprised of a server, the computer program product comprising acomputer readable storage medium having computer readable program codeembodied therewith, the computer readable program code includingcomputer instructions, where a processor, responsive to executing thecomputer instructions, performs operations comprising: a data storeassociating an updated-version-request-time for each object of aplurality of objects wherein each object of the plurality of objectsresides on the data store; the data store maintaining a data structureordering the plurality of objects by updated-version-request-times; thedata store periodically examining the data structure to readupdated-version-request-times; and the data store making a decision tonotify another data store of a change to an object belonging to theplurality of objects based on an updated-version-request-time of theobject.
 16. The computer program product of claim 15 in which theoperations further comprise: the data store sending an updated copy ofthe object to another data store.
 17. The computer program product ofclaim 15 in which the operations further comprise: the data storenotifies another data store of a change to the object in response to adifference between the updated-version-request-time and a current timebeing less than a threshold value.
 18. A processing system comprising: aserver; memory; a network interface device for communicating with one ormore networks; and at least one processor, communicatively coupled withthe server, the memory, and the network interface device, the at leastone processor, responsive to executing computer instructions, forperforming operations comprising: a data store associating anupdated-version-request-time for each object of a plurality of objectswherein each object of the plurality of objects resides on the datastore; the data store maintaining a data structure ordering theplurality of objects by updated-version-request-times; the data storeperiodically examining the data structure to readupdated-version-request-times; and the data store making a decision tonotify another data store of a change to an object belonging to theplurality of objects based on an updated-version-request-time of theobject.
 19. The processing system of claim 18, in which the operationsfurther comprise: the data store sending an updated copy of the objectto another data store.
 20. The processing system of claim 18, in whichthe operations further comprise: the data store notifies another datastore of a change to the object in response to a difference between theupdated-version-request-time and a current time being less than athreshold value.